State DOTs are required to use approved materials for highway guardrail systems. These materials are very expensive when new because they must be originally manufactured for DOT approval according to the high standards for highway barriers set by AASHTO. That organization is tasked with setting the standards for quality, strength, durability, and weather resistance of highway guardrail materials to make them incredibly strong with a nearly infinite lifespan once installed. The stated mission of AASHTO is to advocate transportation-related policies and provide technical services to support states in their efforts to efficiently and safely move people and goods.
As part of that ongoing effort, AASHTO promulgates standards for highway guardrail systems in its AASHTO-AGC-ARTBA Joint Committee Subcommittee on New Highway Materials Task Force 13 Report, entitled “A Guide to Standardized Highway Barrier Hardware.” The Guide specifies the standards for each component that may be used in an approved guardrail system, which standards generally consist of detailed drawings of acceptable materials, along with detailed Specifications and the Intended Use for each.
For example, the most common type of guardrail post currently in use is known as a wide-flange guardrail post. AASHTO sets forth the standards for this post in document PWE-01-04. The wide-flange guardrail post PWE-01 is mandated 72 inches in length, as are most guardrail posts, although it is not uncommon to encounter variations in length from 69 inches to 78 inches and more. More specifically, AASHTO mandates that the PWE-01 post must be what is known as a W6×9 metal guardrail post, whereby the designation “W” stands for wide flange in these I-beam metal posts, “6” stands for the depth of the I-Beam (often thought of as the width of the I-beam), and “9” stands for metal that weighs 9 pounds per foot. The Specifications set forth in document PWE-01-04 state that AASHTMO M 270/M 270M (ASTM A 709/A 709M) Grade 25[250] steel must be used unless corrosion-resistant steel is required, in which case the post must be manufactured from AASHTMO M 270/M 270M (ASTM A 709/A 709M) Grade 50W [345W] steel. The specifications go on to state that the PWE-01 post must be zinc-coated for weather-resistance according to AASHTO M 111 (ASTM A 123), another AASHTO standard.
The same is true of other guardrail system components, including guardrails themselves, which are all equally bound by AASHTO standards. W-beam metal guardrails, for example, must have a specific shape whereby the surface of the guardrails resemble the letter W. The metal specified in the guardrail Specifications is generally the same AASHTO M 270/M 270M grade steel set forth above.
Often a blockout is included as a spacer between the guardrail post and the guardrail. These blockouts must also be constructed of materials meeting AASHTO standards and typically are made of the same incredibly strong AASHTO M 270/M 270M grade steel, but are occasionally made of timber as set forth in AASHTO documents PWB01 and PDB01a-b. To prevent rust and ensure a long lifespan, when these post, blockout, and guardrail materials are metal they must be weather coated according to AASHTO M 111 standards, which means Type II galvanized or Type IV corrosion-resistant.
According to AASHTO document PDB01a-b, if the posts or blockouts are made of timber, however, weather resistance is generally specified as preservation treatment in accordance with AASHTO M 133 after all end cuts are made and holes are drilled. The type of timber is also very important and AASHTO documents PDE01-08 and PDB01a-b, for example, require the use of timber with a stress grade of at least 1160 pounds per square inch (psi) for all timber guardrail posts and blockouts.
All of these materials have in common the characteristics of strength, durability, and long lifespan once manufactured and installed according to AASHTO standards. Once installed, however, all of these materials have the same deficiency in common—they cannot be removed and reused along most highways because removal voids the DOT approval by violating AASHTO and federal highway standards. So when undamaged and perfectly useable materials are removed for projects, such as widening a roadway, those materials are discarded. This is especially true when federal funding is involved because federal oversight prohibits reuse. The outcome provides little potential for a state DOT to recoup any of its initial costs in purchasing the materials and, more importantly, often results in landfill disposal of otherwise useful materials.
The general practice, therefore, is to pay scrap companies to remove used guardrail materials for transport and landfill disposal with other refuse. Higher than normal disposal rates must also be paid because the materials are galvanized for weather resistance and the zinc involved is a mild toxin.
Occasionally, however, if enough material is involved at any given time, state DOTs have been able to recoup a small portion of the original cost by selling these materials to scrap companies for recycling. The amount of money recouped in this manner is generally little more than the cost of having the material removed.
In any event, both of these practices are very wasteful because numerous applications other than highway barriers would benefit from the same quality, strength, durability, and weather resistance found in these guardrail materials. But other applications would not require DOT approval of the materials so employing discarded guardrail materials would not present a problem as long as the guardrails and posts can be reconfigured and resized for such applications.
Farmers, for example, generally build feed lots and loading pens from wood, which is a much weaker material with a lifespan of less than 10 years. Other lots and pens are built from iron or steel, which is somewhat stronger but easily dented because only thin gauge metal is affordable. Thus even if a farmer is able to afford the cost of building a metal feed lot or loading pen, galvanized metal is cost prohibitive so the metal must be repainted often or replaced after approximately 20 years due to corrosion.
It is possible, however, that discarded guardrail materials may be retasked as a building material for many alternate applications such as the above. But many difficulties exist that have heretofore prevented retasking of discarded guardrail materials. The most common problem is that guardrails generally use only six-foot posts that are installed so that the guardrail is set approximately two feet above the ground when used in DOT-approved highway barrier applications. More specifically, a typical highway barrier requires an approximately six-foot post to be installed approximately four feet into the ground to withstand the extreme force involved when contacted by a motor vehicle weighing tons and potentially moving at high speeds. In most cases only a single length of guardrail is needed so only approximately two feet of the post remains above the ground to carry the single guardrail at the proper height to withstand such impacts.
By contrast, a feed lot or loading pen would need to be at least six feet high to prevent the passage of livestock. And although the feed lot or loading pen needs to be much stronger than current wood and metal barriers, the posts would not need to be installed four feet into the ground to withstand the force of crowded livestock, which is drastically lower than the force involved in an automobile collision. As such, a post of approximately seven to eight feet would generally be sufficient so that approximately two feet is buried into the ground and five to six feet remains above ground. In addition, this five to six foot height of guardrail would need to carry multiple lengths of guardrail to effectively block the passage of livestock. Unfortunately, these differences prevent the use of previously DOT-approved guardrail posts because such posts are mostly manufactured in approximately six-foot lengths and because more than a single length of guardrail is needed to provide an effective barrier to livestock.
An affordable barrier system with the strength, durability, and weather resistance of guardrail materials would be useful as long as it could be reconfigured, manufactured and installed for a reasonable price. Yet no prior art systems have met this need with either new or used guardrail materials.
In view of the above, it would be desirable to provide a system and method of installing an affordable barrier system reconfigured from discarded guardrail into a useful size and configuration in alternative applications not requiring DOT approval.
An object of the invention is to provide a system and method of reusing formerly DOT-approved guardrail materials to provide strong, durable, and affordable barrier systems.
A further object of the invention is to provide a system and method of reusing these materials so that state DOTs can recoup more of the initial costs when the material is removed, thereby providing greater funding for current and future roadway projects.
A further object of the invention is to provide a system and method of reusing these materials to avoid landfill disposal, which is wasteful, costly to state DOTs, and harmful to the environment.